Increase in extensively drug resistant Shigella sonnei in Europe
Authors: Hannah Trivett
Journal: The Lancet Microbe (2022)

On Jan 27 2022, the UK Health Security Agency (UKHSA) reported an increase in extensively drug resistant Shigella sonnei infections, primarily affecting gay, bisexual, and other men who have sex with men (GBMSM). Between Sept 1, 2021, and Jan 10, 2022, UKHSA documented 47 cases of extensively drug resistant S sonnei infections. Between April 1, 2020, and Aug 31, 2021, surveillance teams recorded only 16 cases that did not display multidrug resistance, highlighting the rapid increase in resistance over a short time. The outbreak period was extended to March 1, 2022 in the UK, totalling 84 clusters of extensively drug resistant S sonnei. Shigella spp are highly virulent enteric pathogens causing an intestinal infection called shigellosis. Shigella spp are transmitted via the faecal–oral route through contaminated food and water or person-to-person contact. In low-income and middle-income countries, shigellosis is endemic, burdening mostly children aged younger than 5 years with diarrhoea caused by S flexneri and S sonnei. In high-income countries, travel-associated shigellosis is caused by S sonnei in individuals who have travelled to countries with high rates of endemic disease and sporadic outbreaks caused by S flexneri. Additionally, shigellosis can be a sexually transmitted infection (STI), commonly seen in people who engage in oral–anal sexual contact. WHO estimates that there are at least 80 million cases of shigellosis worldwide, with approximately 700 000 mortalities per year. Shigellosis was first identified as a sexually transmissible infection in San Francisco (CA, USA) in 1974, where an increased number of S flexneri were detected in individuals within GBMSM sexual networks. Since then, several sporadic Shigella outbreaks have been reported globally. The first outbreak of S sonnei within the UK was identified in 2004 in London. Shigellosis is generally self-limiting; it is recommended that in moderate to severe cases, the antibiotics azithromycin or ciprofloxacin should be used to treat infections. With the emergence of extensively drug resistant S sonnei, options for patient treatment and management have been substantially reduced. It is well documented that some Shigella isolates are highly resistant to azithromycin and ciprofloxacin, although, in the 2022 outbreak, UKHSA saw an increase in cases with the genomic marker blaCTX-M-27 for ceftriaxone resistance. Although this marker had been previously identified, its occurrence was infrequent. Mateo Prochazka (STI Prevention and Programme Delivery, UKHSA, London, UK) told The Lancet Microbe: “This was the first documentation of sustained transmission of extensively drug resistant shigellosis in sexual networks of gay and bisexual men in the UK. Since infections were resistant to ceftriaxone, there were significant challenges for case management.” Increases in the number of antibiotic resistant Shigella poses concern for the potential antimicrobial resistance (AMR) carriage in the gut microbiome. Hannah Charles (STI Prevention and Programme Delivery, UKHSA) discussed how the presence of the plasmid, encoding blaCTX-M-27 for ceftriaxone resistance raised concern for its effect on horizontal gene transfer in the gut: “I think it's a concern from the perspective of treating individuals and for wider infection control because you might be contributing to or expanding the amount of AMR.” Since the UKHSA press release in January, nine other countries in Europe have reported extensively drug resistant S sonnei: Austria, Belgium, Denmark, France, Germany, Ireland, Italy, Norway, and Spain. Through epidemiological and genomic investigations, many isolates shared similar genomic profiles to those found in the UK and some infected individuals had links to the UK through travel. WHO also requested reporting of incidences through the Global Antimicrobial Resistance Emerging Antimicrobial Resistance Reporting component to improve communication between agencies to impact surveillance and control practices in affected areas. The reporting of the outbreaks was mainly through press releases from national health authorities and WHO. Dissemination of information regarding the outbreak was targeted to specific audiences within the LGBTQ+ community to raise awareness of an STI that is commonly mistaken for food poisoning. Charles commented: “There is not the appetite for the awareness on a wider social network; it's not going to make headline news because it affects a small proportion of the population.” Awareness of Shigella as an STI is poor, possibly due to the overall burden of the infection in comparison to other STIs such as chlamydia and gonorrhoea. Work has been done to establish links with LGBTQ+ media such as Gay Times to spread awareness and improve public engagement surrounding the outbreak. Organisations such as UKHSA and the British HIV Association distributed infographics on social media and Grindr provided STI resources via their website in their community resources section. Using social media to disseminate key information helped to increase public awareness to educate on safe sexual practices and risks associated with S sonnei. Shigella spp is a complex pathogen with multifactorial transmission. As AMR becomes more established in these clusters, it is likely to be transmitted to other Shigella spp and Enterobacteriaceae; it is imperative to raise awareness to limit the spread of infection and highlight the public health concerns of a largely underreported STI. For more on extremely drug resistant Shigella in the UK see https://www.gov.uk/government/news/rise-in-extremely-drug-resistant-shigella-in-gay-and-bisexual-menFor more on sexually transmitted shigellosis see Articles Lancet Infect Dis 2015; 15: 913–21For the global burden of shigellosis see https://www.who.int/emergencies/disease-outbreak-news/item/2022-DON364For more on resistance of Shigella see Sci Rep 2018; 8: 7389For more on Shigella sonnei cases in Europe see https://www.ecdc.europa.eu/en/publications-data/rapid-risk-assessment-increase-extensively-drug-resistant-shigella-sonneiFor the UKHSA shigellosis infographics see https://www.gov.uk/government/publications/shigella-leaflet-and-posterFor the British HIV Association shigellosis infographics see https://www.bhiva.org/shigella-sonnei-a-resource-for-sexual-health-and-HIV-servicesFor the Grindr shigellosis resources see https://help.grindr.com/hc/en-us/articles/360038738273-Sexually-transmitted-infections-STIs-or-STDs For more on extremely drug resistant Shigella in the UK see https://www.gov.uk/government/news/rise-in-extremely-drug-resistant-shigella-in-gay-and-bisexual-men For more on sexually transmitted shigellosis see Articles Lancet Infect Dis 2015; 15: 913–21 For the global burden of shigellosis see https://www.who.int/emergencies/disease-outbreak-news/item/2022-DON364 For more on resistance of Shigella see Sci Rep 2018; 8: 7389 For more on Shigella sonnei cases in Europe see https://www.ecdc.europa.eu/en/publications-data/rapid-risk-assessment-increase-extensively-drug-resistant-shigella-sonnei For the UKHSA shigellosis infographics see https://www.gov.uk/government/publications/shigella-leaflet-and-poster For the British HIV Association shigellosis infographics see https://www.bhiva.org/shigella-sonnei-a-resource-for-sexual-health-and-HIV-services For the Grindr shigellosis resources see https://help.grindr.com/hc/en-us/articles/360038738273-Sexually-transmitted-infections-STIs-or-STDs Intercontinental dissemination of azithromycin-resistant shigellosis through sexual transmission: a cross-sectional studyWe identified transmission-facilitating behaviours and atypical course(s) of infection as precipitating factors in shigellosis-affected MSM. The intercontinental spread of antimicrobial-resistant shigella through established transmission routes emphasises the need for new approaches to tackle the public health challenge of sexually transmitted infections in MSM. Full-Text PDF